1. Field of the Invention
This invention relates to a method for producing Mirabilis Antiviral Protein.
2. Description of the Related Art
Inventors of the present invention previously separated a novel basic protein from Mirabilis jalapa and found that this protein showed antiviral activity (Published Unexamined Japanese Patent Application No. 243100/85). Specifically, this protein is Mirabilis Antiviral Protein (hereafter abbreviated as MAP). The inventors also cultured tissues of Mirabilis jalapa and succeeded in production of MAP utilizing the cultured tissue (Published Unexamined Japanese Patent Application Nos. 125382/87 and 269710/86).
MAP can be mass-produced industrially and easily by growing a large amount of Mirabilis jalapa and extracting MAP therefrom. However, this method has the disadvantage that both much time and an extensive planted area are required for growing Mirabilis jalapa. Methods utilizing cultured tissue disclosed in said Published Unexamined Japanese Patent Application Nos. 125382/87 and 269710/86 also require a long period of approximately 12 days for cell culture.
Meanwhile, with a rapid improvement of gene manipulation techniques, cloning techniques, etc. in recent years, production of available substances using genetic engineering have been tried. Many trials have attained success. Additionally, in protein engineering, the genetic approach is becoming important to study novel proteins. This is due to improvements of analyzing techniques and DNA synthesis techniques which are accomplished by accumulating fundamental studies.
Under the circumstances as said, some trials have been made in the study of MAP to analyze the structure of MAP, to design an MAP gene based on the analyzed MAP structures, and to synthesize it. The present inventors have also made the most of gene recombination and have developed a method for producing MAP by introducing foreign genes into e.g. E.coli to produce MAP therein.
This method, however, suffers from the disadvantage that MAP produced and stored in E.coli inhibits biosynthesis of host cell proteins. Therefore, growth of E.coli is inhibited and the amount of MAP produced therein does not readily increase, which limits the production of MAP.
On the other hand, in order to separate a protein which accumulates in E.coli, a method is conventionally known to make a gene encoding a signal peptide combine with a gene coding for the objective protein and induce the produced protein to secrete. Although many signal peptides are known, it requires practical experiments at present to know whether the desired effect can be obtained.